turre



Feb. 2, 1960 G. J. TURRE, JR 2,923,885

TUBULAR GALVANOMETER STRUCTURE Filed May 13. 1954 INVENTOR. GEORGE J. TUE/PE, JR.

A r ram/E r r, 2,923,885 "Patented Feb. 2, 19

TUBULAR GALVANOMETER STRUCTURE George J. Turre, In, Denver, Colo., assignor, by mesne assignments, to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application May 13, 1954, Serial No. 429,440 1 Claim. c1. 324-97 a relatively low value of magneto-motive force and will 7 have a greater strength.

Another object is to produce a galvanometer which will be more rugged than prior constructions, will be easy to produce and assemble, thus resulting in lower manufacturing costs.

Another and more specific object is to produce an improved galvanometer by substituting for the usual brass or other non-magnetic material, a tube made from a magnetic material such as steel or iron.

Other objects of my invention will become apparent from the following description taken in connection with the accompanying drawings showing a galvanometer embodying my invention.

In the drawings:

Figure l is a side view of a known galvanometer arrangement shown by way of example and in which my invention is embodied;

Figure 2 is an enlarged longitudinal sectional view through the pole pieces and the magnetic gap of the galvanometer;

Figure 3 is a cross sectional view taken on the lines 3-3 of Figure 2 showing additional details; and

Figure 4 is a sectional view, similar to Figure 3, of a galvanometer embodying my invention but not having pole pieces in the tube.

Referring to the drawings in detail, there is disclosed a well known galvanometer construction having opposed permanent magnets indicated as N for north and S for south polarities so as to produce the desired magnetic field in which will be suspended the current carrying vibratory element. Associated with these magnetic poles and positioned therebetween is the usual tube T, the purpose of which is to provide a suitable housing for the suspension and if damping is desired, a container for a suitable damping fluid. The suspension for the galvanometer is generally indicated by the letter U and it can comprise any looped current carrying element C, shown as a coil, suspended by filaments and 11 or like structure such as ribbons, as is known practice. The upper filament 10 is connected to the upper part of the tube T by a grommet and other known structure which may include a yieldable or tensioning element 12. On the filament 10 is secured a mirror M by which light from a source will pass through a window W and be reflected and vibrations of the suspension recorded, as is known practice. The lower filament 11 is connected to the lower end of the tube in a suitable manner to complete the suspension. A suitable adjustment 13 is provided where- I by the tension of the suspension can be set as desired.

The coil will be connected in an electrical circuit, as is known practice.

Within the tube are suitably mounted soft iron pole pieces 14 and 15 whereby a narrow magnetic field gap G will be established and in this gap will be positioned the current carrying element shown as a coil with the plane of the loops of the coil being positioned to be normally at right angles to the magnetic lines of force across the narrow gap when the coil is in a normal non-vibrating condition, that is, when no current is being carried by the coil.

In prior galvanometers of the type described having a tube T, the tube has been made from a non-magnetic material such as brass. With these tubes of non-magnetic material the field strength between the north and south magnetic poles is weaker than it would be if the tube were of magnetic material, the extent that it is weaker being determined by the thickness: of the walls of the non-magnetic material of the tube. I have also discovered that the field obtained when a non-magnetic material for the tube is employed is not entirely uniform and a greater magneto-motive force is necessary to establish the desirable magnetic saturation at the gap.

In accordance with my invention, I overcome all the mentioned undesirable features resulting from the use of a tube T of non-magnetic material by making this tube from a suitable magnetic material, such as iron or steel, and then selecting a proper thickness: of this magnetic material so there will be magnetic saturation in the gap in which the current carrying looped member, such as the coil C, is suspended, all obtainable by a lower value of magneto-motive force than that when the tube is made of non-magnetic material as heretofore has been the practice.

In Figures 2 and 3 I have shown the galvanometer tube as carrying the pole pieces 14 and 15 on the inside thereof in the same manner as when non-magnetic material is used for the tube. This is done to produce-a narrow gap for the coil when such a gap is desired and the tube is to be of relatively large diameter. However, when the tube is made of smaller diameter, these pole pieces can be eliminated and still obtain a magnetic saturation at the gap Where the coil is suspended which will be equal to or greater than that obtained by a nonmagnetic material tube with inner soft iron pole pieces and by the employment of a magneto-motive force of lower value. A galvanometer tube of magnetic material without pole pieces mounted therein is shown in cross section in Figure 4. With elimination of the pole pieces, manufacturing will be more economical, not only due to the elimination of the cost of pieces, but also their cost of assembly.

When a steel or iron tube replaces a non-magnetic material tube, the galvanometer will have a more rugged construction. Also, the field in which the coil or like vibratory element is suspended will be more uniform, due to the fact of the existence of a continuous magnetic path between the poles of the magnet.

What is claimed is:

In a galvanometer: a looped, current-carrying element mounted for vibration about an axis; a suspension structure attached to opposite portions of said current-carrying element and having an axis lying substantially in said axis of vibration; a mirror carried by said suspension structure; a tube of magnetic material attached to said suspension structure and providing a support and a housing for said suspension structure and a container for a damping fluid and having thin, solid walls encircling and spaced from said current-carrying element and of such uniform, small thickness as to cause magnetic saturation in the interior of said tube and in said thin walls and reacting with said current-carrying element; a window in said tube opposite said mirror; and apair of spaced, opposed, permanent magnets having confronting faces defining an air gap between them and engaging the outer surface of said tube and thereby supporting said tube.

References Cited in the file of this patent UNITED STATES PATENTS 1,740,548 Macgahan Dec. 24, 1929 Simpson Mar Faus Dec.

Morrow Apr.

Hendricks Dec Hathaway Dec 

